A new plasma device operated in liquids for biological applications

An in-liquid plasma device has been suggested for the first time to achieve the practical biological applications of sterilization and gene transfection. The device generates planar plasma in liquids from nine via-holes, and produces hydroxyl radicals (OH radicals) in plasma. In the device design, 2D-FEM simulation was performed to determine the device parameters: the device size, 30×30 mm; via-hole diameter, 50 μm; distance between via-holes, 10 mm. It was found that impedance variation at each via-hole can be ignored, since the electric double layer on the device is formed and acts as an impedance buffer layer. Finally, we confirmed that OH radicals were produced and Escherichia coli (E. coli) bacteria were eradicated within 16 minutes.